DALLAS (CBSDFW.COM) — Hundreds of North Texans endured the heat to get their children vaccinated last minute, making sure their kids won’t be turned away on the first day of school for not having updated shot records.

“My rough estimate is that there could be between 2,500 to maybe 5,000 children in Dallas County that have not received their vaccination. We’ll know on Monday for sure,” said Zach Thompson, Director at Dallas County Health and Human Services.

State law requires children to have their shot records updated before they can enter school each year.

Dallas County Health and Human services has seen more than 500 people this week leading up to the first day of school.

With the recent measles outbreak, there is even more urgency for some parents.

“I just hope that everybody gets their kids their immunizations because they are jeopardizing other children,” said Sheniqua Pease, a mother of two who brought her children to be vaccinated.

“The issue that we are having in the Dallas/ Fort Worth area regarding the measles outbreak is that you have homeschoolers who are opting out of their children getting the vaccine,” said Thompson.

According to the state, in the school year that ended in 2012, 2,100 Tarrant County ISD students received what is called a “conscientious exemption” from vaccines. There are 1,500 in Dallas County and 1,300 in Denton County, which is more than 1% of that districts student population.

“Their choice not get their children immunized is impacting other children,” Thompson said.

Thompson says the county may soon look into reaching out to children who are home schooled and others who decline vaccinations to discuss the importance of immunizations.

“That should be a part of a public health legislative agenda so that’s a question that we really have to look at,” he said.